Actuating mechanism for magnetos



P. BROWN.

ACTUATING MECHANISM 0R MAGNETOS.

APPLIC A T l O N F I L E D l U N E 25. 1920.

1,427,718, PatentedAug.29,1922.

ZSHEETS S HEET I.

IN ENTO 4 W ATTORNEYS.

P. BROWN. ACTUATINGMECHANISM FOR MAGNETOS.

APPLICATION FILED JUNE 25. 1920.

Patented Aug. 29, 1922.

2 SHEETS-SHEET 2.

ATTORNEYS entree stares PATENT OFFICE.

rnnnrs BROWN, or siennverinnn, MASSACHUSETTS.

ACTUATING MECHANISM FOR MAGNETOS.

App1icatien filed June 25,

To all 207mm it may concern:

Be it known that I, PHELPS BROWN, a citizen of the United States, residing at Springfield, in the county of Hampden and 5 Stateo'li lllassachusetts, have invented new and useful Improvements in Actuating Mechanism for lilagnetos, or which the following is a specification. p This invention relates to the driving or actuating mechanism of magnetos and, more particularly, to magnetos oi the reciprocatory armature type.

While the invention is capable of general application, it finds one advantageous use in magnetos of the general character d1sclosed in U. S. Letters Patent No. 1,307,343,

granted to me on June 24, 1919. The invention disclosed in such patent is directed,

among other things, to improved means for 0 moving the armature to and from the cores of the maenetos, which means are characterized in that they eliminate, to a large degree. the noisiness of operation heretofore incident to magnetos of the reci'orocatory armature type. That is to say, tl e actuating means is designed with a view to avoiding the noiseproducing sharp blows and impingements hitherto common in, and considered essential to the commercial su cess oi, me netos of this particular character. This invention is directed, among, other things, to the same general problem.

[in object oi. this inventionis to provide improved driving: means, in the nature of a cam, for moving the armature toward the cores of the magneto and subsequently releasing; it for more rapid movementaway from the cores, characterized in that the cam permits the amnature to descend with relative rapidity but without the usual at tending noise.

according to this object. the cam is of such contour to gradually niovethe armature in one direction but is not, as is usual, provided with asharp let oil portion which allows the armature, and the cam follower which it engages, to fall freely and acquire considerable momentum before its fall'is checked by a noise producing im- Specification of Letters Patent.

1119; line ri of Fig. 2;

Patented Aut 29, 1922.

1920. Serial No. 391,712.

pingement. Rather, the cam has a relativelv gradual fall, like an inclined pl-ane, and is permitted to slip on its driving shaft in the direction of rotation. The arrangement is such that, after the high point of the cam passes under the cam follower, the pressure of the latter on the inclined plane forces the cam ahead very rapidly on its driving shaft and thereby accomplishes the desired relatively rapid descent of the cam follower Another object of the invention is to proride in an actin. ing mechanism of the general type described, means for advancing the cam on its drive shaft for timing purp see, such means being in the character a spacer which may be manually interposed between the described. abutments with rapidity and convenience, even while the cam is in motion, or automatically, as desired. A

Other objects and advantages will appear in the following description and'in the illustrative embodiment of the invention in the accompanying drawings, in which,

Fig. 1 is an elevational view of a magneto mounted on an explosive engineand driven therefrom by mechanism embodying the invention;

Figs. 2 and 3 are enlarger. elevational views of the actuating mechanism. Fig. 3 showing the spacing device interposed between the enacting 'abutments to vary the timing of the cam;

Fig. 4 is a cross sectional view taken on F1 5 ma longitudinal section taken on the line 55 of Flg. 3;

Fig. 6 is a fragmentary elevational view, partly in section, illustrative of modilica tion; and

Figs. 7 and 8 are cross sectional views taken on the lines 7-7 and 8-8, respectively, of Fig. 6.

Referring to these drawings: A indicates conventionally an explosive or internal combustion engine, having a crankshaft Z) and another shaft 0 which is driven, as by gears d, from shaft b at appropriate SDGSCl with relation to the frequency at which sparks are to be produced by the magneto for ignition purposes. The magneto, indicated conventionally at I, may be of any suitable type in which an armature e is movable to and from a core, or cores, to vary the reluctance of a magnetic circuit. The magneto may for example be of the type disclosed in the patent above alluded to. l? or the present purposes, it will suffice to state that the armature e is gradually moved toward cores f, as by a cam 10, and cam follower 11., and is later released for movement with relative rapidity away from the cores f, at which timethe ignition spark is generated. As illustrated, the release of the cam follower 11 occurs once on each revolution of shaft 0, although the frequency of release relatively to the revolutions of shaft 0 may be varied, as desired. The movement of the cam follower 11 away from the cores may be accomplished by any suitable means capable of exerting sufficient pressure on cam 10 to move it forwardly on its drive shaft in a manner later to be described. A spring 12, for example, may be utilized to force the follower 11 toward cam 10 as indicated in Fig. 1 or the mechanism illustrated in the aboveunentioneu patent may be utilized for the same purpose.

The mechanism for controlling the move ment of armature 6 will now de described with particular reference to Figs. 2 to 5 inelusive. The cam 10, as best shown in 4 is of the edge type and has its periphery formed to provide a gradual rise 13, which occupies the major portion of the periphery and terminates with the high part Li. and with a fall 15, which connects the part 'llwith the low point 16 of the cam. The por tion 15 is preferably a flat surface and, although of gradual slope, compared to the fall portion of the usual let off cam, is of considerably steeper slope than the rise 13. The cam 10 is intended to rotate in the direction of the arrow (although it is capable of being rotated in the opposite dire *tion) and the portion 15 is so fashioned, as just described or otherwise, if desired, that a suflicient component of the pressure of the cam follower 11 upon it will be afforded t6 move the cam in the direction of its intended rotation, relatively to its driving shaft.

With this object in view the cam 10 is .when positioned. as in mounted so as to be free to turn within limits relatively to its drive shaft 0. As illustrated, the cam if) is mounted to turn freely on a hub 17 and is held against axial. displacement between a collar 18 suitably fixed thereto an d a head, 19 :ii'iten rally formed with, or otherwise fixed to a, hub 17. The latter is fixed to shaft (1 in any suitable way as, for example, by a bolt 20 which passes axially through the hub and threaded into shaft 0. As illustrated, the head of bolt 20 does not directly abut tnc hub 17, but rather acts through the intermediary of a spacing); sleeve 21 to clamp the hub against the end of shaft 0. in order to drive the cam 10 from shaft 0, or the hub 1.? fixed thereto, interengageable abutments are provided one on the cam and one on the cellar portion 19 of hub 17. Thus, a pin i. fined to and projects radially outwards from coll 19 and a pin is fixed to and projects ly outwards from an end face of cam 10 into the path of pin 22.

lVith the am 10 trave lingin the direction of the arrow (Fig. 1;) and the follower l1 engaged with the use 113. the pressure of the follower on the ri e tends to tu n the cam relatively to hub iii in a directl n opposite to the direction of rotation, whereby the pins and ...S are held in engagementand the hub and am rotate in synchronism until the follower reaches the high part Llof the cam. lVhcn, however, the follower l1 rides onto the portion 15, its 'cssuro, havingcomponent in the CllTC -LlOD of rotation of the drive shaft, forces the cam rapidly ahead on the drive shaft. Th 10 thus moves ahead until. the surface comes pes' one-d at right angles to the line of pressure the cam follower 11, at which time there is no force tending to more the cam in either direction. Consequently, the

cam dwells in this position, until the pin overtakes and engages the pin Thus, a

very rapid. drop of the care follower is perinitted and this is accomplished without the usual. attending; nois The follower never leaves engagement with the cam and thus there cannot be the lliLlHC ineideut to a su quent re-engagcment these parts w' i impactof one upon the other, which occurs when one moving under momentum from a free fall is arrr ted by the other.

In order to provide for chansiiing the angular position of the (ill on shaft to effect variations in timing. a spacer 24. is arranged to be interposed etween pins and. 23 shown in Fin The pin 22 and when directly e w in effect the release of the follower l1 such time as to cause a retarded sparlc. These parts. 3. cause an ad vance in the time of th spars.

In order to conveniently interpose the pacer 5243; to advance the spark while the tween the pins 22 and 23.

shaft c is in motion, it is formed as a part of a shell 25, which losely fits over the portion 19 of hub 17 and is capable 0f being moved angularly and axially within limits relatively thereto. To move the shell25 axially, when released, a spring 26 is provided, which acts between the, head of the bolt and the head of the shell 25. A bayonet, or right angularly shaped, slot 27 is provided in the shell, into which slot-a pin 28, fixed in collar 19 extends. Pin 25.5,when engaged in that portion of slot 27 which lies at right angles to the axis of theshell, prevents axial movement of the latter under the force of spring 26 and holds the shell and the spacer 24 in an inactive position, as shown in Fig. 2 The shell is further provided with a U- shaped recess 29 to receive pin 22, when the spacer 24 is interposed between. the latter and pin 28. The shape of recess 29 is" not particularly material, however, and it may be otherwise formed as long as it permits the shell" to move forwardly sufficiently to permit the interposition of spacer 24 be The shell25, when turned sufficiently to bring pin 28 in line with that portion of'slot 27 which is parallel to the axis of the shell, is likewise positioned so that recess 29 is in line with pin 22. The shell 25 is preferably provided with a knurled portion 30, whereby it may be conveniently gripped manually. p here it, is desired to advance the spark automatically, I provide the slightly modified arrangement shown in Figs. 6, 7, and 8. The shaft 0, as before, loosely carries the cam which is provided with an abutment in the shape of an arcuate projection on a side face of the cam. The latter is held from endwise movement on shaft 0 between collars 36 and 37, both fixed thereon. The collar 37, on that face adjacent to the cam, carries an abutment 38, similar to and adapted for engagement by the abutment The cam 10 is driven in the direction of the arrow by the engagement of the abutment 38 with abutment 35. During each revolution, cam 10 is forced ahead in the same manner as before, and the abntments 35 and 38 are separated. The spacer, for interposition between these abutments, consists of a keystone shaped member 39 which is fixed to a pin 4L0 slidably mounted in collar 37 for movement parallel to the axis of shaft 0'. 1 Pin 40 has an enlarged rounded end 4:1 protruding, from that end of the .collar 37 remote from cam 10 and a spring 42 acting between this end 41 and a shoulder in the collar holds the spacer 39 retracted, as shown, in a recess in the collar and out of the path of the abutments and 88. For automatically moving the spacer 39,

a ring li-3 is loosely mounted on shaft 0 and carries a cam 44: which, when the ring is shifted around the shaft 0 and thus relaoted at 46 relatively heavy-members 4:7. The

free ends of these members are connected to disc by means of links ae; A spring l9, connecting the pivot of onemember 47 to the free end of the other, normally holds the members 47 in their inner positions and ring 43 in such position that pin 4L0 is not advanced by cam 44. When the engine reaches a predetermined speed, which'may be gauged as desired, the members 45? tend to move outwardly by centrifugal force and shift ring as around shaft 0. This shifting, of course, cannot take place until the abutments and 38 separate but immediately that such separation occurs the ring 43 shifts and cam 44; moves the spacer 39 between the abutments and holds it thus positioned as long as the speed of the engine is maintained at or above the chosen predetermined speed.

In operation, the shell 25 is positioned, asshown in Fig. 2, on'starting of the engine A the cam 10 being so located on its drive s aft as to cause the production of a retarded spark from the magneto I. In the case of the device shown in Figs. 6 to 8, this is automatically accomplished. The cam operates the armature e of the magneto already set forth in detail. After the engine has been started and' it is desired to advance the spark, the shell 25 is momen tarily lightly gripped sufliciently to cause pin 28 to move out ofthe bayonet portion of slot 27 and free the shell for axial movement, which occurs rapidly and auto matically under the action of spring 29. The interposition of spacer 2% between the pins 22 and 23 occurs, of course, when the latter separate as the cam 10 is moved rapidly ahead on its drive shaft. The operation of the device shown in Figs. 6 to 8' has already been explained.

The invention has been disclosed herein for illustrative purposes, but the scope of the invention is defined by the appended claims rather than by the foregoing description. e

What I claim is,"

1. In a magneto, a'movable armature, an actuatingcam, and a cam follower therefor, a driving member with relation to which the cam is free to turn, adevice on the cam and a device on said member to drive the cam from the latter by abutment, and means forcing said follower against the cam; the

latter'having a part which, when engaged by said follower, will, by the force of said means, move the cam ahead of its driving member and permit a rapid movement of the follower without disengagement from the cam.

2. In a magneto, a movable armature, an actuating cam therefor, a driving member with relation to which the cam is free to turn, a device on the cam and a device on said member to drive the cam from the latter by abutment, and means forcing said armature toward the cam, the cam having a part so inclined to the direction of pressure from the armature that pressure from the latter on such part will move the cam ahead relatively to its driving member.

3. In a magneto, a movable armature, an actuating cam for moving the armature in one direction and releasing it for movement in the other direction, means for moving the armature in the second direction, a driving member with relation to which the cam is free to turn, interengageable devices one on the cam and one on said member to drive the former from the latter, said cam having a surface for moving the armature in the first direction, and a second surface so inclined to the direction of pressure from the armature that the cam will be moved ahead of its driving member by the force that moves the armature in the second direction.

41-. The combination, with a cam follower, of a cam for moving it in one direction and releasing it for movement in an opposite direction, a driving member with relation to which the cam is free to turn, and interengageable devices one on said cam and one on said member for driving the former from the latter, the contour of said cam for moving the follower in the first-named direction being such that a component of the pressure of the follower on the cam tends to hold said means in engagement, the contour of the cam for releasing the follower for move ment in the other direction being such that the pressure of the follower moves the cam ahead relatively to the driving member in the direction of its rotation.

5. In a magneto, a movable armature provided with a cam follower, a drive shaft, a cam thereon with which said follower is con stantly engaged under all operating conditions and means periodically permitting a relative slip about the axis of said shaft between said cam and follower so that the change in relative positions of the cam and follower be periodically increased over that effected by said drive shaft.

6. In a magneto, a movable armature, driving means, an actuating cam for the armature free to turn relatively to said means, interengageable devices one on said cam and one on said means arranged by abutment to drive the former from the latter, and spacing means movable between said devices to vary the position of the cam on its driving means.

7. In a magneto, a movable armature, driving means, an actuating cam for the armature free to turn relatively to said means, interengageable devices one on said cam and one on said means arranged by abutment to drlve the former from the latter, spacing means movable between said devices to vary the position of the cam on its driving means, and means to releasably hold the spacing means in an inactive position.

8. In a magneto, a movable armature, driving means, an actuating cam for the armature free to turn relatively to said means, interengageable devices one on said cam and one on said means arranged by abutment to drive the former from the lat ter, s )acing means movable between said devices to vary the posit-ion of the cam on its driving means, means to move said spacing means toward said devices, and manually releasable means to hold said spacing means in an inactive position.

9. In a magneto, a movable armature, an actuating cam, and a cam follower th refor, a driving member with relation to which the cam is free to turn, a device on the cam and a device on said member to drive the cam from the latter by abutment, and means forcing said follower against the cam, the latter having a part so inclned to the direction of pressure of the follower that pres-,

sure of the latter on such part will move the cam ahead of its drive shaft and separate said devices a second. member axially movable relatively to said driving member and carrying a spacer for interposition between said devices when separated, means to move said members the one relatively to the other, and manually releasable means to hold the second member in inactive position.

10. In a magneto, a movable armature, an. actuating cam, a cam follower therefor, a driving member with relation to which the cam is free to turn, a device on the cam and a device on said member to drive the cam from the latter by abutment, means forcing said follower against the earn, the latter having a part so inclined to the line of travel of the follower that pressure of the latter on such part will move the cam ahead of its drive shaft and separate said devices, a second member axially and angularly movable relatively to said driving member and carrying a spacer for optional interposition between said devices when separated, means to move said members axially, the one relatively to the other, means operable by relative angular movement of said members to release the latter for axial movement.

11. In a magneto, a movable armature, driving n1eans, an actuating cam for the armature free to turn relatively to said means, interengageable devices one on said cam and lIO one on said means arranged by abutment to drive the former from the latter, and spacing means automatically movable between said devices to vary the position of the cam on its driving means.

12. In a megneto, a movable armature, driving means an actuating cam for the armature free to turn relatively to said means, interengageable devices one on said cam and one on said means arranged by abutment to drive the vformer from the latter, and spacing means operable as the engine reaches a predetermined speed to move between said devices to vary the position of the cam on its driving means.

In testimony whereof I have affixed my signature.

PHELPS BROWN. 

